White oil stabilizing treatment



United States atent 3,110,664 WHITE H. STABlLlZING TREATMENT Robert L. Carden, Poteau, Okla, Oliver C. Kerfoot, New

Orleans, La., and Irwin R. Supernaw, Shawnee, Okla,

assigmors to Continental Oil Company, Ponca City,

Okla, a corporation of Delaware No Drawing. Filed May 27, 1960, Ser. No. 32,091

3 Claims. (Cl. 208-296) This invention relates to improved hydrocarbon oil compositions. More particularly, this invention relates to a process for stabilizing a highly refined white mineral oil to an extent whereby the development of odor which normally occurs when the oil is subjected to aotinic radiation exposure is beneficially minimized. Specifically, the present invention pertains to a process for preparing improved lightand heat-stable white mineral oils which comprises contacting the oil with mercuric chloride at elevated temperature and thereupon recovering the stabilized oil free of the mercuric salt. This invention further relates to improved mineral oil products of the aforesaid process.

The oils contemplated as most suitable for use in accordance with our invention are generally known as highly refined, industrial type white mineral oils and are available commercially in various grades differing chiefly with respect to viscosity properties. from their source, namely, crude oil stocks, they are transparent, colorless and substantially odorless oily liquids. Either paraifin-base crudes, naphthene-base crudes or mixtures of said crudes may be employed in obtaining the white mineral oil. Although the quality of the finished product depends primarily upon the degree of care and skill employed in the refining process, certain of its basic properties are determined by the type of crude used. For example, a naphthene-base crude provides a white mineral oil of relatively high specific gravity and viscosity characteristics. On the other hand, a Pennsylvania type parafin base crude yields a white oil of generally lower viscosity properties and specific gravity. In

addition to the physical properties noted for the various mineral oils derived from the particular sources mentioned, these crudes also yield oils differing somewhat in other properties. For example, white oils derived from parafiin-base crudes exhibit excellent heat resistance and are noted for their affinity for certain waxes. Particularly because of the latter mentioned attribute, an oil of this type is favored in certain applications such as for example in the preparation of cosmetic formulations.

The first step in the production of white oil consists in the removal of the lighter portions of the crude such as gasoline, naphtha, kerosene and certain like fractions such as for example fuel oils. This segregation of the enumerated fractions is customarily accomplished by a heat process referred to as fractional distillation. After the lighter fractions of the crude have been separated as indicated, the oil residue is further distilled. The lower boiling fractions of said residue serve as the raw oil from which the white oils are ultimately obtained via a refining operation.

The primary purpose in refining the raw oil fractions is to remove various reactive and unsaturated hydrocarbons and impurities therefrom, which components are responsible for the color, odor, taste and other objectional properties associated with the unrefined oil. Although the specific details of the refining procedure may vary considerably among the individual manufacturers of the white oil, it will almost always include treatment of the oil with sulfuric acid, washing with alkalies and solvents, and the application of adsorbents.

The purpose of the sulfuric acid treatment is to remove all of the unsaturated, aromatic and other reactive hydrocarbons and most of the impurities that are present in the When initially produced oil. The action of the treating acid is both chemical and a physical one. In its chemical role, the sulfuric acid reacts with a large proportion of the objectionable components present to yield complexes capable of ready removal. The acid additionally serves as asolvent for the said reaction products or complexes and also efiects removal of resinous and asphaltic substances and other like impurities from the oil.

In most of the refining practices the oil is treated with large quantities of either concentrated or fuming sulfuric acid (oleum). The quantity and concentration of acid used, the temperature, the length of treatment and the method of application depends upon the type of crude used and type of oil and degree of refinement required. Ordinarily, 30 to 70% of acid based on the weight of the oil is used. The contact time of acid with oil varies extensively as indicated and ranges from as brief as a few minutes in continuous treating to about one hour in batch processes.

Following the acid treatment, the oil is usually further refined by some sort of adsorption process in order to remove minute traces of carbon, coke, resinous and asphaltic substances, coloring matter, moisture, etc. The commonly used adsorbents are of mineral origin and include fullers earths in natural state or in acid-activated form, e.g., bauxite, bentonite, etc. Adsorbents of organic origin such as charcoal, activated carbon and the like as well as such substances as silica gel, alumina gel, or similar synthetic adsorbents are also used.

White mineral oils are employed in a legion of industrial applications. The particular application involved more or less dictates the grade of mineral oil to be used, especially as regards its viscosity characteristics. Accordingly, one can find numerous commercial products generally sold to meet relatively narrow viscosity specifications. Thus one may readily avail of proprietary products ranging in viscosity from as low as 30 SSU units Saybolt at F. to a viscosity of as high as 500 SSU. Of this broad range of viscosi'ties that may be found in products of this type, there are two general classifications, namely, light viscosity or simply light white mineral oils, i.e., those having a Say-bolt viscosity of not more than about SSU at 100 F. and 'heavy white mineral oils which have higher viscosity than that specifically stated. Details with respect to the aforesaid viscosity characterization of oil products may be found in ASTM test D445-46T.

Apart from lubricating applications which usually include most lubricants for food processing apparatuses wherein a medicinal grade of oil is required, there are many other type applications in which a so-called technical grade of white mineral oil is perfectly satisfactory. The technical grade designation connotes an oil which is highly refined and substantially chemically inert, but not so absolutely inert as to permit its use for medicinal purposes as an internal lubricant. The technical grade oils are used extensively in cotton processing, leather dressings, and especially in the preparation of cosmetics or cosmetic bases, such as makeup preparations, cold creams, hair preparations and the like. Our invention especially pertains to technical grade white mineral oils useful in the latter applications among others of a similar nature.

It is known that all white mineral oils, however fully refined, have a tendency to deteriorate with a development of odor which development is greatly accelerated upon exposure of the oil to light, particularly at elevated temperature. The odor experienced is that of a disagreeable hydrogen sulfide odor; and although while the amounts of hydrogen sulfide generated in such a deterioration process are extremely small they are nevertheless perceptibly obnoxious.

We have found that improved white mineral oils evidencing a high degree of stability toward the development of odor upon exposure to actinic radiation such as sunlight can be obtained by treating the refined oil with substantially dry mercuric chloride. We are aware that the prior art has taught that sour hydrocarbon oils can be rendered sweet by treatment with salts such as the mercuric chloride of this invention. However, it was totally unexpected that when a hydrocarbon oil such as the highly refined odorless oils to which this invention is directed is treated with the mercury salt, said treatment markedly inhibits the development of subsequent odori-ferous tendencies. Con sequently, it can be appreciated that our process is not merely that of removing odor bodies present as such in the oil but is a much more complex proposition, namely, that of effectively thwarting untoward odor development.

In accordance with this invention, the refined mineral oil is contacted with mercuric chloride and such treatment can follow a number of dilferent procedures. Thus our process can be effected by suitably agitating or stirring an admixture of the mercuric chloride and the mineral oil. In such a process the amount of mercuric chloride employed, the temperature of the oil and the time of treating are all inter-related factors. Considering particularly the amount of mercuric chloride in relation to the amount of oil treated, same is dependent upon the treating temperature, i.e., the oil temperature, the extent of etiective contact between the oil and the mercuric salt and further upon.

the length of time in which the process is carried out. Ordinarily from about 1 to 20% of mercuric chloride based on the oil represents a suitable range of amounts that can be utilized. When using an amount of mercuric chloride in the lower portion of said stated range, it may be necessary to employ higher temperatures and/ or longer periods of contact treatment. With the foregoing in mind, suitable temperature conditions range between about 75 C. and 150 C., and periods of treatment range from about 1 minute to 30 minutes. Generally, amounts of mercuric chloride ranging from about 1 to 10% based on the oil are ample. A particularly preferred amount of the mercuric salt is from about 5 to In using an amount of salt within the preferred range, a sufiicient corresponding time of treatment is from about 5 to 20 minutes, and more preferably at least about 10 minutes.

In the above described method of carrying out the present invention, the treated oil can be recovered essentially free of the mercuric chloride treating agent by a number of methods. One method consists of merely filtering the admixture of salt and oil through a filter medium or aid as a bed of finely divided silica or like material. Another applicable method consists of washing the admixture of oil and mercuric salt with water, removing the water layer containing dissolved mercuric chloride and drying to remove traces of water from the oil.

Another embodiment of treating the while mineral oils in accordance with this invention is one of a continuous nature whereby the white mineral oil is allowed to seep through a bed of dry mercuric chloride, thence through a contiguous bed of a filtering medium such as finely divided silica, charcoal and the like which serves to remove all traces of the mercuric salt from the oil. Time of contact in the continuous process can be regulated by adjusting the rate of percolation of the oil through the mercuric chloride layer. This time of contact can be varied over a wide range depending particularly on the temperature of the oil undergoing treatment. As in the batch process, temperatures ranging from about 75 to 150 C. can also be satisfactorily utilized in the continuous process. Ef-

dfective contact time may also range, as in the batch process, from about 1 minute to about 30 minutes.

In order to further illustrate the nature of this invention, the following examples are given in which all parts -re parts by weight. Any details or enumeration contained in these examples should not be construed as limitative of the invention except as provided for in the appended claims.

Example I A white mineral oil having a Saybolt viscosity of SSU at 100 in the amount of 100 parts was mixed with 10 parts of dry mercuric chloride and stirred vigorously at 100 C. for 15 minutes. The mixture was then washed with water to remove the mercuric salt and the oil layer which had been rendered substantially free of the mercuric salt was then dried over anhydrous sodium sulfate.

Example I] As in Example I, 100 parts of the white oil were mixed with 5 parts of dry mercuric chloride and similarly stirred for 15 minutes at 100 C. The oil mercuric chloride admixture was then filtered through a filtering bed to remove the solid salt.

Example 1H Each of the oil products of Examples 1 and H were placed in stoppered glass bottles and exposed for 2 hours at 205 F. to an ultraviolet light source (Weatherometer A bottle of untreated oil was exposed along with the treated oils for comparison purposes. After the indicated time of exposure, the oils were examined for hydrogen sulfide formation with lead acetate paper. The two treated samples of Examples I and H showed no hydrogen sulfide present whereas the untreated oil showed heavy hydrogen sulfide formation.

What is claimed is:

1. A process for enhancing the lightand heat-stability of a white mineral oil which comprises contacting said oil with substantially dry mercuric chloride at a temperature between about C. and 150 C. for a contact time of from about 1 to 30 minutes, thereupon recovering said oil free of mercuric chloride.

2. A process for enhancing the lightand heat-stability of a colorless and odorless white mineral oil free of unsaturated and aromatic hydrocarbons and having a Saybolt viscosity at F. of from 30 to 500 SSU which comprises agitating a mixture of said oil and from about 1% to 20% of dry mercuric chloride based on the oil at a temperature between about 75 C. and C. for

a period of from about 1 to 30 minutes, thereupon recovering said oil free of mercuric chloride.

3. A process for enhancing the lightand heat-stability of a colorless and odorless white mineral oil free of unsaturated and aromatic hydrocarbons and having a Saybolt viscosity at 100 F. of from 30 to 500 SSU which comprises agitating a mixture of said oil and from about 1% to 10% of dry mercuric chloride based on the oil at a temperature between about 75 C. and 150 C. for a period of from about 5 to 30 minutes, thereupon recovering said oil free of mercuric chloride.

References Cited in the file of this patent UNITED STATES PATENTS Hoover May 26, 1936 Brown Mar. 2, 1954 OTHER REFERENCES 

1. A PROCESS FOR ENHANCING THE LIGHT- AND HEAT-STABILITY OF A WHITE MINERAL OIL WHICH COMPRISES CONTACTING SAID OIL WITH SUBSTANTIALLY DRY MERCURIC CHLORIDE AT A TEMPERATURE BETWEEN ABOUT 75*C. ANDF 150*C. FOR A CONTACT TIME OF FROM ABOUT 1 TO 30 MINUTES, THEREUPON RECOVERING SAID OIL FREE OF MERCURIC CHLORIDE. 